Enhancement of immune responses to hepatitis B DNA vaccine by superantigen SEA in mice / 生物工程学报

To investigate the adjuvant effect of plasmid DNA encoding superantigen SEA (D227A) (pmSEA) on immune responses induced by HBV DNA vaccine containing HBV preS2 and S antigen in BABL/c (H-2d). BALB/c mice were immunized intramuscular injection with HBV DNA vaccine (pHBVS2S) mixed with or without pmSEA plasmid. Antibodies againat HBV PreS2 and S antigen in the sera were accessed by Anti-HBs ELISA, and the HBsAg specific cytotoxic T lymphocytes (CTLs) activity was determined by 5 Chromium Release Assay. The HBs peptide-specific IFN-gamma secreting T cells were detected by ELISPOT. Anti-HBs antibody titers and CTLs activity in mice immunized with pmSEA + pHBVS2S group were significant higher (P < 0.05) than pHBVS2S DNA vaccine group. The ratio of IgG1/IgG2a (0.282) was apparently different from the group immunized with peptide (10). Mice immunized with HBV DNA vaccine plus adjuvant produce higher titer of IgG1 and IgG2a antibodies against HBV S antigen 1.36 and 1.73 time higher than that without adjuvant respectively. HBs peptide--specific IFN-gamma secreting T cells increased 2 - 3 times by the pmSEA adjuvant, compared to DNA vaccine group. HBV DNA vaccine (pHBVS2S) induces humoral and cellular immuno-responses in BALB/c mice, and the responses could be significantly boasted by the plasmid encoding mSEA. Therefore the pmSEA was a potential adjuvant for DNA vaccines.

Functional expression of DNA binding domain of Zif268 in Escherichia coli / 生物工程学报

As the ubiquitous nucleic acids recognizing motif, Zinc finger protein play important role in regulation of gene expression. The study of recognization specific will greatly facilitate understanding the delicate interaction of Zinc finger protein and DNA. By the choice of expression vector, the induction and culture conditions, the DNA binding domain of Zif268 was expressed in Escherichia coli partly solubly. The gel mobility shift assay shows that purified DNA binding domain can bind its natural target sequence specifically, which indicates the DNA binding domain remains its DNA binding activity in Escherichia coli. The functional expression of DNA binding domain of Zif268 will greatly facilitate the development of in vivo genetic selection assay for the study of Zinc fingers-DNA interaction.

Gene cloning, soluble expression and activity analysis of rSEA / 生物工程学报

The superantigen,such as staphylococcal enterotoxins, had been identified as possible anti-cancer molecules in many reports. In this paper, we cloned the entA gene encoding Staphylococcal enterotoxin A from the genomic DNA of Staphylococcus aureus(ATCC13565) by PCR, the sequence cloned was accordance with that reported in Genebank. The entA gene could be expressed effectively after inserted into plasmid pET-22b( + ), The rSEA was expressed as inclusion bodies when induced by IPTG at 37 degrees C and became soluble after induced at low temperature, the soluble part is about 55% of total rSEA products. Only one band was detected by western-blotting in expression product of BL-21 (DE3) with pET-SEA. The soluble rSEA was purified by Ni2+ chelating sepharose column. No other protein except rSEA was seen in SDS-PAGE gel stained by both Coomassie brilliant blue and silver salt, which showed that the rSEA was purified effectively. Homology modeling of rSEA determined the structure change was conducted, which indicated there was no apparent structure change between rSEA and native SEA. This result was also confirmed by proliferation assay of PBMC, for the rSEA could induced proliferation of PBMC as effectively as native SEA. The increasing anti-tumor activity of rSEA was also detected after the spleen cell activated in vivo by rSEA, which was accordance with others reports. This work paved the way for the further study of anti-cancer with rSEA.